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On 30 June I finally used my new Maccy-Kontiki kiln to make biochar from my tree litter down in the meadow.

In progress

The following observations may be of interest:

1. Overnight rain had wetted the wood but the day was sunny and mild with only a slight breeze. So I did not bother with any wind shields.

2. I had no trouble lighting a fire in the bottom of the kiln with some dry twigs I had brought with me for the purpose plus some newspaper plus a firelighter!

3. After the process had started there was some light smoke but it dissipated quickly.

4. When the process was going well I noticed the flames seemed to want to rotate around the four sides of the kiln. I also noticed a build-up of ash over the burning wood. So I started worrying that the process was not happening as it should. I have since concluded that a characteristic of this process is that it needs to burn the surface layer of the wood in order to heat it sufficiently for the volatiles to escape and be burnt.

5. I noticed that the sides of the kiln have warped but no damage is yet apparent.

6. When the burning wood had reached almost to the top of the kiln I used the hose to quench the fire and filled the kiln with water. I had forgotten to put bricks under the kiln so drainage took longer than I had expected. Like overnight!

7. The next day I shovelled the char into a large bag placed in the wheelbarrow. And then I found I could not budge it! So I transferred the char into 3 smaller bags.

In progress

After quenching

After bagging

Conclusion: The quality of the char appears to be very good so my concerns about ashing have been allayed.

I have weighed the wet char and will weigh it again when dry and then report back here.